As is known, wireless communication systems use base stations to send messages, including paging messages, to mobile stations that are located within cells. The paging messages are used to locate a mobile station within a system. A base station receives a paging request message from a page controller and sends out a paging message within the cell that it operates in an attempt to determine if the mobile station is in that cell. In some embodiments of synchronous paging, the plurality base stations send paging and repaging messages within their respective cells at the same time and at given time intervals until a the designated mobile station responds. Upon a response from the mobile station, the page controller of the wireless communications system does not send an additional paging and repaging request messages to the base stations. Thus, the paging for the mobile station ceases. In wireless communication systems including Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA) and Global System for Mobile Communications (GSM) the base stations are synchronous to one another. In other words, a paging message is sent from a plurality of base stations at the same time in order to locate a given mobile station at any given time. Newer and more advanced wireless communication systems such as CDMA2000, Wide Band CDMA (WCDMA) and Universal Mobile Telecommunication Systems (UMTS) also use synchronous base stations to send messages including paging messages to the mobile stations.
In order to overcome other issues related to the advancement of wireless communication systems, newer wireless communication systems such as Long Term Evolution (LTE) are considering using asynchronous base stations. In an asynchronous arrangement, the plurality of base stations send messages including paging messages to mobile stations at different times. Asynchronous base stations allow base stations to be deployed in locations where GPS signals are not available such as subway stations and in situations where it is difficult for base stations and mobile stations to be synchronized. In an asynchronous environment, the paging signals can be sent from different base stations at various different times. If the paging interval for a given paging area is 4 seconds, the paging message can be sent from any one of the asynchronous base stations within that 4 second paging interval, e.g. 0.5 sec., 1 sec., 1.5 sec. etc. up to the end of the interval.
As can be appreciated, a mobile station can respond to any of the paging messages sent by any of the base stations. If a mobile station responds to the paging message at the beginning of the paging interval, e.g. 0.5 sec. into the interval, base stations that are scheduled to send paging messages at the end of the interval will still be sending the paging message even after the mobile station has been located. These paging messages are not needed and they will not be responded to because the mobile station has been located.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.